AST Cleaned Up

ast.fs

open System

type ASTNode =
    | Add of (ASTNode * ASTNode)
    | Sub of (ASTNode * ASTNode)
    | X 
    | Constant of int

let rec Evaluate node x =
    match node with
    | Add (l,r) -> (Evaluate l x) + (Evaluate r x)
    | Sub (l,r) -> (Evaluate l x) - (Evaluate r x)
    | X -> x
    | Constant v -> v

let rec ASTToString node =    
    match node with
    | Add (l,r) -> "(" + (ASTToString l) + " + " + (ASTToString r) + ")"
    | Sub (l,r) -> "(" + (ASTToString l) + " - " + (ASTToString r) + ")"
    | X -> "X"
    | Constant v -> string v

let rec ConstantFolding node =
    match node with 
    | Add (l,r) -> match (ConstantFolding(l),ConstantFolding(r)) with
                   | (Constant v1,Constant v2) -> Constant(v1+v2)
                   | (optL,optR) -> Add(optL,optR)                            
    | Sub(l,r) ->  match (ConstantFolding(l),ConstantFolding(r)) with
                   | (Constant v1,Constant v2) -> Constant(v1-v2)
                   | (optL,optR) -> Sub(optL,optR)                            
    | X -> X
    | Constant v -> Constant(v)


[<EntryPoint>]
let main argv =
    let equation = Sub(Constant(3),Add(Constant(5),Constant(2)))
    let optimized = ConstantFolding equation
    //let result = Evaluate equation 2
    printfn "%A" (ASTToString optimized)
    Console.ReadLine()

    0 // return an integer exit code